title: Inhibitory effects of forced swim stress and corticosterone on the acquisition but not expression of morphine-induced conditioned place preference: involvement of glucocorticoid receptor in the basolateral amygdala.
abstract: Addiction is a common chronic psychiatric disease which represents a global problem and stress has an important role to increase drug addiction and relapse. In the present study, we investigated the effects of physical stress and exogenous corticosterone on the acquisition and expression of morphine-induced conditioned place preference (CPP). Also, we tried to find out the role of glucocorticoid receptors (GRs) of basolateral amygdala (BLA) in this regard. In the CPP paradigm, conditioning score and locomotion activity were recorded by Ethovision software. Male adult rats received forced swim stress (FSS) as a physical stress or corticosterone (10 mg/kg; ip) as a dominant stress hormone in rodents, 10min before morphine injection (5 mg/kg; sc) during three conditioning days (acquisition) or just prior to CPP test in the post-conditioning day (expression). In FSS procedure, animals were forced to swim for 6 min in cylinder filled with water (24-27 °C). To evaluate the role of glucocorticoid receptors in the BLA, different doses of mifepristone (RU38486) as a GR antagonist were injected into the BLA (0.3, 3 and 30 ng/side) during 3-day conditioning phase before FSS or injection of corticosterone in morphine-CPP paradigm. The results showed that FSS and corticosterone reduce the acquisition but not expression of morphine-induced CPP. Moreover, blockade of GRs in the BLA could diminish the inhibitory effects of FSS or corticosterone on the acquisition of morphine-induced CPP. It seems that stress exerts its effect on reward pathway via glucocorticoid receptors in the BLA.
authors.affiliation: Department of Physiology, Faculty of Medicine, Hormozgan University of Medical Sciences, Bandar Abbas, Iran.
authors.forename: Ghassem
authors.initials: G
authors.lastname: Attarzadeh-Yazdi
authors.forename: Sara
authors.initials: S
authors.lastname: Karimi
authors.forename: Pegah
authors.initials: P
authors.lastname: Azizi
authors.forename: Saeid
authors.initials: S
authors.lastname: Yazdi-Ravandi
authors.forename: Soghra
authors.initials: S
authors.lastname: Hesam
authors.forename: Abbas
authors.initials: A
authors.lastname: Haghparast
mesh_terms: D000679:Amygdala / Q000187:drug effects / Q000378:metabolism*; D000704:Analysis of Variance; D000818:Animals; D003216:Conditioning, Operant / Q000187:drug effects*; D003345:Corticosterone / Q000378:metabolism* / Q000494:pharmacology; D006727:Hormone Antagonists / Q000494:pharmacology; D008297:Male; D015735:Mifepristone / Q000494:pharmacology; D009020:Morphine / Q000494:pharmacology*; D009043:Motor Activity / Q000187:drug effects; D009294:Narcotics / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D011965:Receptors, Glucocorticoid / Q000378:metabolism*; D013315:Stress, Psychological / Q000503:physiopathology*; D013550:Swimming / Q000523:psychology
chemical_list: D006727:Hormone Antagonists; D009294:Narcotics; D011965:Receptors, Glucocorticoid; D015735:Mifepristone; D009020:Morphine; D003345:Corticosterone
keywords: Basolateral amygdala; Corticosterone; Glucocorticoid receptor; Morphine; Physical stress; Reward